I called Katadyn and they're closed for the day. I have one and will be going out tomorrow in an area that **could** have mercury contaminated water. Besides the Hiker, I also have the Pocket Filter and MSR Sweetwater.

I'm fairly certain most if not all my water can come from springs, right out of the ground. If one of my filters reduced mercury though, I'd take it for a peace of mind......

It does not and cannot. Neither does most anything else available.Don't drink that sort of water.

Edits: Activated charcoal will remove SOME ions, but there is no guarantee as to how much will be removed. Risky business.As OP has pointed out, if the contamination level is rather low and you are only drinking a litre or two, the amount of mercury you would absorb would be very small, possibly within safe exposure guidelines. But you don't know.In an *emergency* you could use clear water from the top, avoiding any sediments or organic matter.Do you feel lucky?

After I posted but before you replied, I decided to give MSR a call....since I have a Sweetwater too. The guy told me the Sweetwater would "reduce some" but he/they had no idea how much. He thought any filter with carbon in it would reduce to some degree. That was the impression I was under too. But, I really don't know....

If you are thinking about filtering water out of a lake that has high levels of mercury it shouldn't be a problem unless you are filtering at the bottom of the lake. Mercury is much more dense than water and will sink. Just don't eat the fish...

Technically the MSR guy is correct; if the filter contains activated carbon it can remove /some/ mercury.

However, if the levels of mercury in the water are above safe levels, you should not assume that the filter will reduce them in any significant amount, particularly if it has not specially formulated for mercury removal. (E.g. in coal plants, the activated carbon used in scrubbers will be impregnated with iodine.)

Yeah, not worth worrying about for a water source you're barely going to use. If you're going to start drinking out of there for years or decades, then yes, do worry. The slight amount of mercury you may consume will eventually be naturally eliminated from your body. If nothing else, remember that mercury used to be a medicine. The crew on the Lewis & Clark expedition put a ridiculous amount of that stuff into their bodies, and some of them lived long lives...a lot of the short-lived folks died of 'adventurous' things.

The short answer is yes, carbon can adsorb mercury from water but is more commonly used for vapor-phase mercury removal. I can't find literature on whether it captures methyl mercury (the bioavailable form). See section 8.

http://www.epa.gov/tio/download/remed/542r07003.pdf

Regrettably the question as posed here is unanswerable. FWIW the most common concern with methyl mercury is exposure via the food chain, not directly from drinking water contaminated by it. It bioconcentrates in fish.

Nobody in customer service will be able to provide guidance because they cannot possibly know. What kind of carbon is in the filter, how much is there, what's the flow rate and contact time, what's the contaminant concentration in water, what's the water chemistry, how fresh is the carbon...the variables pile up into a gigantic heap.

The array of carbon types is vast, in itself.

http://www.calgoncarbon.com/carbon_products/water.html

I've worked with groundwater and soil contamination cleanup using GAC, but typically for solvent and fuels contamination. The interesting bit is when it removes radionuclides and the carbon vessels become "hot" and the carbon itself becomes radioactive waste.